Non-woven fibers coated with a polymer of ethylenically unsaturated blocked aromatic diisocyanates

ABSTRACT

Ethylenically unsaturated blocked aromatic diisocyanates are prepared which readily polymerize to form homopolymers and interpolymers with copolymerizable vinylidene monomers. Polymers can be prepared via emulsion polymerization, and exhibit excellent stability to hydrolysis when stored in latex form. The polymers cure at temperatures as low as 80° C., and under acidic, neutral, or basic pH conditions. Homopolymers and interpolymers of the defined diisocyanates are useful as adhesives, and interpolymers of the ethylenically unsaturated blocked aromatic diisocyanates with acrylate monomers are particularly useful as binders for nonwoven fibers.

This is a division of application Ser. No. 904,128, filed May 8, 1978,now abandoned, which in turn is a division of application Ser. No.734,916 filed Oct. 22, 1976, now U.S. Pat. No. 4,101,491, which in turnis a division of Ser. No. 550,627, filed Feb. 18, 1975, now U.S. Pat.No. 4,008,247, which in turn is a division of Ser. No. 412,325, filedNov. 2, 1973, now abandoned.

BACKGROUND OF THE INVENTION

Prior art disclosing polymerizable blocked isocyanates is as follows:U.S. Pat. Nos. 2,483,194; 2,556,437; 2,882,260; 3,261,817; 3,299,007;3,542,739 and 3,694,146, and British Pat. No. 1,288,225. Other relevantart is disclosed in U.S. Pat. Nos. 3,519,478; 3,694,389 and 3,711,571.

The novel ethylenically unsaturated blocked aromatic diisocyanates canbe distinguished from other known polymerizable isocyanates by theirease of polymerization and copolymerization with vinylidene monomers,particularly in emulsion polymerization systems. The prepared polymersare quite stable to hydrolysis and can be stored in latex form.

Interpolymers of the novel diisocyanates with acrylate monomers haveparticular utility as binders for non-woven fibers such as paper,cotton, synthetic fibers, and the like. The fibers are coated orimpregnated with the interpolymers which can then be cured attemperatures as low as 80° C. and under acidic, neutral, or basic pHconditions. This is in contrast to the known acrylic or nitrile latexbinders which require highly acidic (pH of about 2) conditions toexhibit a strong fast cure at low temperatures. The highly acidicenvironment is undesirable as it can degrade some fibers, especiallycellulose-type fibers, it can interfere with efforts to thicken thelatex for more convenient use, and it can cause corrosion.

SUMMARY OF THE INVENTION

Ethylenically unsaturated blocked aromatic diisocyanates are preparedhaving the formula ##STR1## where R is hydrogen or a methyl or ethylradical, A is a carbonyloxyalkylene radical containing 2 to about 8carbon atoms or an aralkylene radical; B is a bivalent aromatic radicalselected from the group consisting of arylene, napthalene, and thestructure ##STR2## where Y is O, S or --CH₂)_(n), where n=0 to 3, and Xis the radical fragment remaining by the removal of a hydrogen atom fromthe nitrogen atom of an oxime, benzimidazole, pyrazole, benzotriazole,caprolactam or thiocaprolactam, or p-nitroaniline.

The defined diisocyanates are readily polymerized, especially viaemulsion polymerization techniques, to form polymers of from about 0.1percent to 100 percent by weight (i.e., homopolymers) of thediisocyanate and up to 99.9 percent by weight of a copolymerizablevinylidene monomer.

DETAILED DESCRIPTION OF THE INVENTION

The ethylenically unsaturated blocked aromatic diisocyanates have theformula ##STR3## wherein R is hydrogen or a methyl or ethyl radical; Ais either a carbonyoxyalkylene radical containing 2 to about 8 carbonatoms or an aralkylene radical containing 7 to about 12 carbon atoms; Bis a bivalent aromatic radical selected from the group consisting ofarylene, napthalene, and the structure ##STR4## where R is defined asabove, Y is O, S, or --CH₂)_(n), n=0 to 3, and X is the radical fragmentremaining after a hydrogen atom is removed from the nitrogen atom of anoxime, benzimidazole, pyrazole, benzotriazole, caprolactam,thiocaprolactam, or p-nitroaniline. The aromatic rings in A and/or B canbe further substituted with 1 to 4 carbon atom alkyl radicals. Morepreferredly, R is hydrogen or a methyl radical, B is selected from thegroup consisting of phenylene, tolylene, naphthalene, and the definedstructure where Y is --CH₂)_(n) group and n=0 to 1.

Examples of the unsaturated blocked aromatic diisocyanates are:

When "A" is a carbonyloxyalkylene radical: ##STR5## and the like.

The ethylenically unsaturated blocked aromatic diisocyanates areprepared in a two-step process wherein first a hydroxy-containingvinylidene monomer is reacted with an aromatic diisocyanate, and theproduct obtained then reacted with a blocking agent. Reference is madeto U.S. Pat. No. 2,958,704, and the process disclosed therein.

The hydroxyl-containing vinylidene monomer has the formula ##STR6##where A and R are defined as above. When A is a carbonyloxyalkyleneradical, examples of the monomer include 2-hydroxyethyl acrylate,2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 4-hydroxybutylmethacrylate, 4-hydroxybutyl ethacrylate, 5-hydroxypentyl acrylate,5-hydroxy-3-methylpentyl acrylate, 6-hydroxyhexyl acrylate, and thelike. When A is an aralkylene or alkyl substituted aralkylene radical,examples include o, m, and p-vinyl benzyl alcohol, o-methyl-p-vinylbenzyl alcohol, and the like.

The hydroxyl-containing monomer is reacted with an aromatic diisocyanateusing at least a slight molar excess of the diisocyanate. Temperature ofreaction is from about 0° C. to 100° C. The reaction must be conductedfree of water. Solvents for the reaction are benzene, toluene,chlorobenzene, chloroform, carbon tetrachloride, trichloroethylene, andthe like. The aromatic diisocyanates have the formula OCN--G--NCOwherein B is defined as above. Examples of these diisocyanates are2,4-toluene diisocyanate, 2,6-toluene diisocyanate,naphthalene-1,4-diisocyanate, diphenyl diisocyanate,diphenylmethanep,p'-diisocyanate, dimethylphenylether diisocyanate,3,3'-dimethyl-4,4'-biphenyl diisocyanate, p-isocyanatobenzyl isocyanate,bis(2-isocyanatoethyl)benzene, and the like. Halogenated diisocyanatessuch as 1-chloro-2,4-diisocyanatobenzene, tetrachloro-1,3-phenylenediisocyanate, 2,4,6-tribromo-1,3-phenylene diisocyanate, and the like,can be used.

The more preferred aromatic diisocyanates are those wherein one of theisocyanate groups has a 1 to 4 carbon atom alkyl group ortho to one ofthe isocyanate groups. Examples of these are 2,4-toluene diisocyanate,2,6-toluene diisocyanate, and ortho-methyl substituents of otheraromatic diisocyanates such as 2-methyl-1,4-naphthalene diisocyanate,5-methyl-diphenyl diisocyanate, 2,6-dimethyltoluene-1,4-diisocyanate,3-ethyl-1,4-toluene diisocyanate, 1,6-dimethyl-2,4-toluene diisocyanate,3,6-dimethyl-5-ethyl-1,4-naphthalene diisocyanate, and the like.

The ortho-substituted aromatic diisocyanates are preferred, as theunhindered isocyanate group will react first and, preferentially, withthe hydroxyl group of the monomer. The hindered isocyanate group tendsto remain apart from this reaction and good yields of the unsaturatedaromatic isocyanate are obtained. The product obtained is reacted with acompound having a labile hydrogen atom to block the remaining isocyanategroup.

The choice of a compound to be used as a blocking agent is particularlycrucial to the successful use of a blocked isocyanate in nonwoven fiberbonding applications. If the blocking agent-isocyanate reaction productis too stable, the agent will not release quickly and/or at moderatetemperatures. High temperatures and long heating times can degrade thepolymers and the nonwoven fibers. Many tertiary alcohols, phenols,amines, and imines were found to be unsatisfactory for this reason. Ifthe blocking agent-isocyanate reaction product is too labile, the agentwill release prematurely and the isocyanate will be free to react. Thisresults in instability of the interpolymer latex or solution andproblems in applying and heat curing. The novel interpolymers of thisinvention provide an improved balance between polymer stability andquick, moderate temperature cure cycles. This balance is struck and theexcellent properties obtained only when a combination of an aromaticdiisocyanate and the specified blocking agents are employed.

Blocking agents for the ethylenically unsaturated aromatic diisocyanatesare oximes, benzimidazole, pyrazoles, benzotriazoles, caprolactam,thiocaprolactam, and p-nitroaniline.

The oximes are aldoximes or ketoximes of the formula ##STR7## wherein R'is an alkyl radical containing 1 to about 8 carbon atoms, a cycloalkylradical containing 4 to 8 carbon atoms, an aryl radical containing 6 toabout 12 carbon atoms, or where R' and R", together with the carbonatom, form a carbon ring of 4 to 8 carbon atoms, and R" is hydrogen orthe same as R'. Examples of the oximes are acetoxime, methylethylketoxime, methylpropyl ketoxime, methylisobutyl ketoxime, ethylhexylketoxime, cyclohexanone oxime, benzophenone oxime, benzoaldoxime, andthe like.

Pyrazole and 1 to 4 carbon atom alkyl substituents thereof can beemployed. Examples are pyrazole, 3-methyl pyrazole, 3,5-dimethylpyrazole, and the like.

The benzotriazoles are benzotriazole and 1 to 4 carbon atom alkyl,halogen, and nitro substituents thereof. Examples of the benzotriazolesare benzotriazole, 5-methylbenzotriazole, 6-ethylbenzotriazole,5-chlorobenzotriazole, 5-nitrobenzotriazole, and the like.

The blocking agents are employed on about a 1 to 1 mole basis ofisocyanate to agent. The reaction temperature is from about 30° C. toabout 110° C. Reaction time is from about 1 hour to about 15 hours.Suitable solvents for the reaction are aromatic hydrocarbon solventssuch as benzene and toluene.

The ethylenically unsaturated blocked aromatic diisocyanates can bepolymerized using emulsion (latex), suspension, solution, and bulktechniques known to those skilled in the art. The polymerization can beperformed as a batch reaction, or one or more ingredients can beproportioned during the run. Temperature of polymerization ranges fromabout -10° C. to about 100° C., whereas a more preferred range is fromabout 5° C. to about 80° C.

The polymerization is initiated by free-radical generating agents.Examples of such agents are organic peroxides and hydroperoxides such asbenzoyl peroxide, dicumyl peroxide, cumene hydroperoxide, paramethanehydroperoxide, and the like, used alone or with redox systems; diazocompounds such as azobisisobutyronitrile, and the like; persulfate saltssuch as sodium, potassium, and ammonium persulfate, used alone or withredox systems; and the use of ultraviolet light with photo-sensitiveagents such a benzophenone, triphenylphosphine, organic diazos, and thelike.

Typical emulsion polymerization ingredients would include a persulfatesalt or organic peroxide and usually a redox system, water adjusted to adesired pH with acids or bases and usually buffered with inorganic saltsand either anionic, cationic, or nonionic surface active agents wellknown to the art.

The polymerization normally is continued until about 90% or moreconversion of monomers is obtained. The resulting latex can becoagulated to isolate the polymer. Typical coagulation procedures aresalt/acid coagulations, use of polyvalent metal salts such as MgSO₄, useof alcohols such as methanol and isopropyl alcohol, and freezeagglomeration techniques. The polymer is then usually washed with waterand dried.

The polymers are comprised of from 0.1 percent to 100 percent by weight(i.e., homopolymers) of an ethylenically unsaturated blocked aromaticdiisocyanate(s), as defined, and up to 99.9 percent by weight, and morepreferably up to about 70 percent by weight, of a copolymerizablevinylidene monomer. This monomer is a vinyl monomer having a terminalvinylidene (CH₂ =C<) group. Examples of these monomers are acrylates andmethacrylates such as ethyl acrylate, n-butyl acrylate, octyl acrylate,dodecyl acrylate, methyl methacrylate, phenyl acrylate, cyclohexylacrylate, and the like; vinyl and allyl esters such as vinyl acetate,vinyl propionate, vinyl butyrate, allyl acetate, and the like; vinylketones such as methyl vinyl ketone, propyl vinyl ketone, and the like;vinyl and allyl ethers such as vinyl methylether, vinyl ethylether,vinyl isobutylether, allyl methylether, and the like; vinyl aromaticssuch as styrene, α-methylstyrene, p-chlorostyrene, vinyl toluene, vinylnaphthalene, and the like; vinyl nitriles such as acrylonitrile,methacrylonitrile, α-chloroacrylonitrile, and the like; dienes such asbutadiene, isoprene, chloroprene, 2-isopropyl-1,3-butadiene, and thelike; α-monoolefins such as ethylene, propylene, 1-butene, 1-hexene, andthe like; vinyl halides such as vinyl chloride, vinyl fluoride,vinylidene chloride, and the like; and divinyls such as divinyl benzene,divinyl ether, diethylene glycol diacrylate, and the like. In addition,because the isocyanate is blocked, so-called reactive monomers can becopolymerized with the acrylates and unsaturated isocyanate. Examples ofthese monomers are vinyl carboxylic acids such as acrylic acid,methacrylic acid, ethacrylic acid, 2-hexanoic acid, and the like; vinylamides such as acrylamide, methacrylamide, N-methyl methacrylamide,diacetone acrylamide, and the like; hydroxyl-containing vinyl monomerssuch as allyl alcohol, vinyl benzyl alcohol, β-hydroxyethyl acrylate,α-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, β-hydroxyethylmethacrylate; N-methylol acrylamide, and the like.

The polymers are high molecular weight solids having dilute solutionviscosities (DSV) of over 0.5 measured on a 0.2 gram sample of thepolymer in 100 milliliters of solvent at 25°0 C. The polymers are curedat temperatures as low as 80° C. and can be cured under acidic, neutral,or basic pH conditions.

The polymers can be admixed with cure ingredients and compoundingingredients using two-roll mills, internal mixers such as Banburys andextruders, and like equipment.

The polymers, as isolated solid rubbers, can be cured to prepare usefulvulcanizates. Compounding ingredients well known to the art can be used,such as fillers, oils and plasticizers, antioxidants, and the like.Standard mixing and cure techniques are employed. Upon heating thepolymer, the blocking agent is released. Hydroxyl, carboxyl, and aminecontaining materials are used as curing agents. For example, glycols,polyols, polyalkylene amines, hydroxyl and carboxyl containingpolyesters and polyethers, hydroxyl, carboxyl, and amine terminatedvinylidene polymers, etc., and water itself, are all known and suggestedreactants for isocyanate-containing materials. If the interpolymeritself contains hydroxyl, carboxyl, or amine groups, the polymer can beconsidered self-curing. Upon heating, the isocyanate is released and thepolymer can undergo intra- and inter-molecular crosslinking.

The polymers do not have to be isolated, but can be readily stored inlatex or solution form. The novel polymers have excellent stability inlatex form. In non-woven binder applications, the polymers areconveniently used as latexes or solutions to coat or impregnate thefibers. Fillers, extenders, and other ingredients such as stabilizingagents, thickeners, antioxidants, and the like, are readily admixed withthe latexes or solutions prior to use.

In non-woven fiber binder applications, the ethylenically unsaturatedblocked aromatic diisocyanates are preferably copolymerized with anacrylate monomer. The interpolymer comprises from about 0.5 percent toabout 50 percent by weight of the diisocyanate(s) as defined, and fromabout 50 percent to about 99.5 percent by weight of an acrylatemonomer(s). More preferably, the interpolymer contains from about 1percent to about 30 percent by weight of the diisocyanate, from about 70percent to about 99 percent by weight of an acrylate monomer, and up to20 percent by weight of another copolymerizable vinylidene monomer, allpresent as interpolymerized units.

The acrylate monomer has the formula ##STR8## wherein R is H, --CH₃ or--C₂ H₅, and R_(a) is an alkyl radical containing 1 to about 24 carbonatoms, an alkoxyalkyl or alkylthioalkyl radical containing a total of 2to about 12 carbon atoms, or a cyanoalkyl radical containing 2 to about12 carbon atoms total. The alkyl structure can be linear or branched.Examples of the acrylates are methyl acrylate, ethyl acrylate, n-propylacrylate, isopropyl acrylate, isobutyl acrylate, n-pentyl acrylate,isoamyl acrylate, n-hexyl acrylate, 2-methylpentyl acrylate, n-octylacrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate,n-tetradecyl acrylate, n-octadecyl acrylate, n-eicosyl acrylate, and thelike; methyl methacrylate, ethyl methacrylate, n-hexyl methacrylate,n-octyl methacrylate, n-dodecyl methacrylate, n-octadecyl methacrylate,ethyl ethacrylate, n-butyl ethacrylate, and the like; methoxymethylacrylate, methyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate,butoxyethyl acrylate, ethoxypropyl acrylate, methoxyethyl methacrylate,methylthioethylacrylate, hexylthioethyl acrylate, and the like; and αand β-cyanoethyl acrylate, α,β, and γ-cyanopropyl acrylate, cyanobutylacrylate, cyanohexyl acrylate, cyanooctyl acrylate, cyanoethylmethacrylate, and the like. Often mixtures of two or more monomersand/or types of acrylate monomers are employed.

More preferably, the interpolymer contains from 70 percent to about 99percent by weight of an acrylate monomer(s) wherein R_(a) is an alkylradical containing 1 to about 18 carbon atoms or an alkoxyalkyl radicalcontaining 2 to about 8 carbon atoms. Examples of the more preferredmonomers are methyl acrylate, ethyl acrylate, n-propyl acrylate,isopropyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexylacrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate,n-dodecyl acrylate, n-octadecyl acrylate, methoxyethyl acrylate,ethoxyethyl acrylate, methoxypropyl acrylate, ethoxypropyl acrylate, andthe like. Both an alkyl acrylate and an alkoxyalkyl acrylate can beused. Especially good results are obtained when employing ethylacrylate, octyl acrylate, 2-ethylhexyl acrylate, and/or methoxyethylacrylate.

The interpolymers are applied to the non-woven fibers using dip coating,knife edge coating, roller coating, soaking, spray coating, and likeknown techniques. Cure conditions depend in part upon the specificblocking agent and aromatic diisocyanate used to prepare the monomer.However, temperatures from about 80° C. to about 150° C. and morepreferably from about 100° C. to about 125° C. are usually employed.Cure times range from about 3 minutes to about 30 minutes. An excellentcure is readily obtained at 100° C. in about 3 minutes at an acidic,neutral or basic pH.

Examples of non-woven fibers are papers such as Kraft paper, crepepaper, and the like, rag fibers, cotton, wool, regenerated cellulose,glass fiber, asbestos, and synthetic fibers such as polyesters, and thelike. In addition to binding fibers to impart tensile strength, edgetear strength, and the like, the interpolymers are also useful aspigment and filler binders and as fabric adhesives.

The polymers can be copolymers of the essential blocked diisocyanatewith acrylate monomers and from about 0.5 percent to about 10 percent byweight of a hydroxyl, carboxyl, amine or amide containing monomer. Afterapplying such an interpolymer to a non-woven substrate and heating it,the blocking agent is released and the free isocyanate crosslinksthrough these reactive groups to cure the polymer. However, if thepolymer does not have these groups present thereon, compounds containingthe groups can be readily added to the latex or solution prior to use.These compounds are crosslinking agents, and include aliphatic andphenolic diols and polyols, diamines and polyamines, di- andpolymercaptans, di- and polycarboxylic acids, and polymeric materialssuch as polyether polyols, polyester polyols, polyester amides,polyether amides, and the like. Examples of crosslinking agents arealkylenediols such as 1,4-butanediol, 1,6-hexanediol,4-methyl-1,4-pentanediol, 1,10-decandiol, and the like; alicyclic diolssuch as 1,4-cyclohexanediol, 2-hydroxymethylcyclohexanol, and the like;phenolic diols such as p-hydroxybenzyl alcohol, hydroquinone,2,2'-dihydroxydiphenyl, methylenebisphenol, p,p'-isopropylidenebisphenol, and the like; polyols such as 1,3,5-pentanetriol,1,3,5-trishydroxybenzene, glycerol, sorbital, and the like;alkylenediamines such as ethylenediamine, 1,2-butylenediamine,2-methyl-1,4-diaminobutane, hexamethylenediamine, decamethylenediamine,dodecamethylenediamine, and the like; alicyclic diamines such as1,4-diaminocyclohexane, 1,4-diaminoethylcyclohexane, and the like;aromatic diamines such as m-phenylenediamine, m-xylylenediamine,3,3'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, p,p'-bisaminomethyldiphenylmethane, and the like; heterocyclic diamines such as piperazine,aminoethylpiperazine, and the like; polyamines such asdiethylenetriamine, triethylenetetraamine, and the like; andalkanolamines such as tris(hydroxyethyl)amine,bis(hydroxyethyl)methylamine, tris(hydroxypropyl)amine,1-amino-2-hydroxypropane, 1-aminomethylcyclohexanol, m-aminophenol,2-amino-6-hydroxypyridine, and the like. The more preferred crosslinkingagents are the alkylenediols, the alkylenediamines, and thealkanolamines.

The crosslinking agent can be added directly to the latex (or solution).It can be dissolved in a solvent such as chloroform ortrichloroethylene, or suspended in water using an emulsifying agent, andthen added to the latex or solution. No reaction takes place until theblocking agent is released in the cure process. The crosslinking agentsare used on about a mole to mole basis of isocyanate to hydroxy, amino,etc., group. Higher levels may be used, but it is not necessary forobtaining fast strong cures.

Of course, water alone can act as a crosslinking agent for the polymers.In the presence of water, the blocked diisocyanate can react to form anamine structure which can then further react with another blockeddiisocyanate group to crosslink the polymer. The water can be added tothe polymer, or it can be present as residual water in the polymer orsaturated non-woven. Atmospheric moisture can also act to crosslink thepolymers.

As the novel interpolymers have particular utility as binders fornonwoven fibers, testing was directed to evaluation of the interpolymersin latex form as paper saturants. Actual testing included original andwet tensile strength, using an Instron tensile tester at a pull rate of12 inches per minute. Wet tensile followed TAPPI procedure T465-m44(specimens soaked in water for 16 hours before testing).

The following examples serve to more fully illustrate the invention.

EXAMPLE I

A series of ethylenically unsaturated blocked aromatic diisocyanates wasprepared. The general reaction scheme is to first react a mole of ahydroxyl-containing vinylidene monomer with about two moles of anaromatic diisocyanate, and secondly, react the intermediate product withabout 1.1 mole of a defined blocking agent per mole of the intermediate.

A. Preparation of4-(O-methacryloyloxyethyl)urethanotolyl(2-carbamoyl)-1-tolyltriazole.The synthesis consists of a two-step reaction. Toluene, 1080 grams and2,4-toluene diisocyanate, 1160 grams (6.66 moles), were put into areactor vessel equipped for stirring and temperature control. The vesselwas then flushed with nitrogen gas and the intermediate product reactionconducted under nitrogen gas. The mix was heated to 60° C. whilestirring, and 433 grams (3.33 moles) of β-hydroxyethylmethacrylateslowly added over 5.5 hours. Temperature of the mixture rose to 65° C.and was controlled there throughout the addition. The mixture was thenstirred for one hour. Total reaction time was about 7 hours.

The reactor mixture (a solution) was cooled to 5° C. and allowed tostand for about 16 hours. White crystals formed in the solution. Themixture was then cooled to -30° C. and the crystals filtered out andwashed with hexane. The intermediate product was dried to yield 754grams of a white crystalline solid having a melting point of 71°-72° C.Analyzed for isocyanate content and for unsaturation, the intermediateproduct proved to be about 99% pure. The yield was 74% by weight basedon the theoretical weight as measured on the hydroxy compound.

The intermediate product (i.e., theβ-hydroxyethylmethacrylate/2,4-toluenediisocyanate reaction product),22.3 grams (0.0735 mole) was dissolved in 350 milliliters of toluene atabout 30° C. and the solution placed into a reactor vessel.Tolyltriazole, 10.75 grams (0.0808 mole) was dissolved in 50 millilitersof toluene at about 30° C. and the solution then added to the reactorvessel. The mixture was stirred for 3 hours at 30° C. and then at 50° C.for 0.5 hour. A white precipitate forms during the stirring time. Totalreaction time is about 4 hours.

The reaction mixture was cooled to 0° C. and the white precipitateisolated by filtration. The product was washed with acetonitrile anddried at 25° C. under a vacuum to yield 25.6 grams of a crystallinesolid having a melting point of 132°-133.5° C. The yield was 80% basedon the amount of intermediate product used. Analysis by unsaturationshowed the product to be about 99% pure. The product has the structure##STR9##

B. Preparation of4-(O-methacryloyloxyethyl)urethanotolyl(2-carbamoyl)-2-butanone oxime.The intermediate product prepared above was employed.

Toluene, 2686 milliliters, and 517 grams (1.7 moles) of the intermediateproduct were placed in a reactor vessel and stirred. Methylethylketoxime, 152 grams (1.74 moles) was dissolved in 260 milliliters oftoluene and the solution added to the reactor vessel slowly over a 1.5hour period. Temperature of the reaction was kept at 28°-29° C. Themixture was then stirred for 16 hours at about 25° C., followed bycooling to -30° C. A white precipitate formed which was filtered out anddried to yield 494 grams of product (a 74% yield). The crystallineproduct has a melting point of 80.5°-82° C., and analyzed byunsaturation to be about 98% pure. The theoretical nitrogen content ofthe product is 10.7% by weight and the analyzed nitrogen content wasmeasured to be 10.6% by weight. The product has the structure ##STR10##

C. Following the procedure given in B above, the following compound wasprepared by reacting the intermediate product with acetoxime: ##STR11##

D to E. Following the procedure given in B, the intermediate product wasreacted with methylisobutyloxime and dimethylpyrazole, respectively, toyield: ##STR12## melting point of 75°-79.5° C., and ##STR13## meltingpoint of 109°-110.5° C.

F. Following the procedure given in A above, β-hydroxyethyl acrylate and2,4-toluene diisocyanate were reacted together to form an intermediateproduct which was then reacted with methylethyl ketoxime. The product is##STR14## melting point of 108°-113° C. The compound was tested to be95% pure using a standard isocyanate analysis test.

G. Following the procedure given in A above, p-vinylbenzyl alcohol wasreacted with 2,4-toluene diisocyanate, followed by reaction withmethylethyl ketoxime. The product is ##STR15## melting point of79.5°-83° C.

EXAMPLE II

The ethylenically unsaturated blocked aromatic diisocyanate prepared inExample I in procedure B was interpolymerized with a vinylideneterminated monomer, using an emulsion polymerization system. The recipeis as follows:

    ______________________________________                                        Ethyl acrylate, grams  94.1                                                   Diisocyanate B.sup.a, grams                                                                          5.9                                                    Water, milliliters     175                                                    Sodium lauryl sulfonate                                                                              30                                                      milliliters.sup.b                                                            Naphthalene sulfonate, 9                                                       milliliters.sup.b                                                            Sodium hydrosulfite,   8.3                                                     milliliters.sup.c                                                            Sodium formaldehyde sulfoxalate,                                                                     10                                                      milliliters.sup.d                                                            Sodium salt of ethylene diamine                                                                      8.3                                                     tetraacetic acid and sodium                                                   gluconate, milliliters.sup.e                                                 p-methane hydroperoxide,                                                                             0.2                                                     milliliters                                                                  ______________________________________                                         ##STR16##                                                                     .sup.b 10% by weight in water                                                 .sup.c 0.5% by weight in water                                                .sup.d 1.0% by weight in water                                                .sup.e 0.24 and 0.13 grams in 100 milliliters of water                        .sup.f 50% by weight                                                     

The diisocyanate was dissolved in the ethyl acrylate, and the solutionadmixed with the water, sodium lauryl sulfonate, sodium hydrosulfite,and naphthalene sulfonate. 17 milliliters of the mixture was placed in areactor vessel followed by the sodium formaldehyde sulfoxalate, sodiumsalt of ethylene diamine tetraacetic acid and sodium glyconate, andp-menthane hydroperoxide. An immediate exotherm occurred and temperatureof the reaction was controlled at 27°±3° C. Using a stirred droppingfunnel, the remaining mixture was slowly added to the reactor vesselover a 1 hour period. After the addition was complete, the reactor mixstood for 16 hours. Total conversion of monomers to polymer was 96%,based on the total solids of the mix.

EXAMPLE III

Interpolymers of ethylenically unsaturated blocked aromaticdiisocyanates (as prepared in Example I) and ethyl acrylate, wereprepared following the procedure of Example II. The following polymericsamples were prepared and evaluated in their latex form.

    __________________________________________________________________________    Polymer                                                                            Wt. Percent                                                              Sample                                                                             Ethyl Acrylate                                                                        Diisocyanate.sup.a                                               __________________________________________________________________________    A    94                                                                                     ##STR17##                                                       B    95                                                                                     ##STR18##                                                       C    94                                                                                     ##STR19##                                                       D    94                                                                                     ##STR20##                                                       E    95                                                                                     ##STR21##                                                       F    94                                                                                     ##STR22##                                                       G    94                                                                                     ##STR23##                                                       __________________________________________________________________________     .sup.a Weight percent of diisocyanate = 100%  weight percent of ethyl         acrylate                                                                 

The latex samples were used at a total solids content of about 20% byweight. The non-woven fiber employed was saturation grade, bleachedKraft paper of 11 mils thickness. 8 inch by 1 inch strips of the paperwere soaked in each sample latex. Solids pickup was about 50% by weightfor each test strip. The strips were then dried at room temperaturefollowed by curing at selected temperatures and times. When an addedcrosslinker was employed, it was dissolved in or added to the latex as asolution or suspension prior to soaking the paper strips.

Evaluation consisted of wet tensile strength testing following Tappiprocedure T465-m 44. The impregnated paper strips were soaked overnightin water and then pulled on an Instron tensile tester at a jaw speed of12 inches per minute. Test strip samples were run in triplicate and thearithmetric average reported.

The crosslinker employed in this series of experiments is eitherresidual water (i.e., no crosslinking agent was added) or triethanolamine. When triethanol amine was used, it was simply dissolved in thelatex, prior to soaking the samples, at none, one, or two moleequivalents of crosslinker per mole equivalent of isocyanate group onthe polymer.

The data obtained is listed in the following table.

    ______________________________________                                                              Wet Tensile Strength                                    Latex   Parts by Wt. of                                                                             3 Minute Cure At                                        Sample  Triethanol amine.sup.a                                                                      100° C.                                                                         125° C.                                                                       150° C.                          ______________________________________                                        A       none          18       20     20                                              0.75          21       20     21                                              1.50          22       20     22                                      B       none          20       22     23                                              1.50          22       24     25                                      C       none          15       21     27                                              0.75          18       23     29                                      D       none          20       22     21                                              0.75          20       21     21                                      E       none          22       23     24                                              1.50          20       23     22                                      F       none          21       22     23                                              0.75          21       24     24                                      G       none          19       23     22                                              0.75          20       23     24                                      ______________________________________                                         .sup.a Parts by weight per 100 parts by weight of polymer in the latex   

The data shows that excellent wet tensile strength is exhibited by allof the samples. The paper strip, without being impregnated by the novelpolymers, has a wet tensile strength of about 0.5 psi. The Example showsthe excellent results obtained using the novel polymers in latex form asnon-woven fiber binders. The strength obtained is as good as or betterthan results obtained using commercial latexes, especially at low curetemperatures. For comparison, a commercial acrylic latex would exhibit,cured at 100° C. using no crosslinker, a wet tensile strength of about 4psi at a basic pH to a high of about 16 psi at an acid pH.

EXAMPLE IV

Following up Example III in more detail, sample latex A was used toprepare wet tensile samples at various pH's of the latex. Using 0.90parts by weight of 1,6-hexanediol as a crosslinker, after cure at 100°C. for 3 minutes, the wet tensile strength values were: pH of 5, 20 psi;pH of 7, 20 psi; and pH of 9, 19 psi. Repeating the test using 0.75parts by weight of triethanol amine as the crosslinker, the values were:pH of 5, 21 psi; pH of 7, 21 psi; and pH of 9, 21 psi. In contrast, twocommercial acrylic latexes were also evaluated as to their ability toimpart wet tensile strength over a range of pH values with the followingresults: pH of 5, 11 psi and 6 psi, respectively; pH of 7, 8 psi and 6psi, respectively; and pH of 9, 4 psi and 4 psi, respectively. Theexample shows that not only do the polymers of the invention impartgreater wet tensile strength to non-wovens than known commerciallatexes, compared at a 100° C. cure temperature, but the novel polymersare also not sensitive to pH as the commercial acrylic latexes are. At acure temperature of 80° C., a test sample using the novel polymerprepared as sample B had a wet tensile strength of 14 psi (cured 3minutes). The difference between the novel polymers of the invention andthe commercial latexes diminishes as the temperature of cure increasesand the pH of cure decreases. However, fast cures at low temperaturesover a range of pH conditions is highly desirable.

EXAMPLE V

The ultimate tensile strength and wet tensile strength of a boundnon-woven fiber is a function of both the polymeric binder and thecrosslinking agent employed. Of the known crosslinking agents, the useof alcoholic amines is preferred with the novel polymers of thisinvention. Using the polymer latex prepared as sample A in Example III,and following the procedure given in Example III, various crosslinkingagents were evaluated at one equivalent weight as to their ability todevelop rapid and high strength cures.

    ______________________________________                                        Sam-                                                                                        Parts by                                                                             Wet Tensile Strength                                     ple  Crosslinking Agent                                                                           Weight.sup.c                                                                           80°                                                                         100°                                                                        125°                                                                        150°                       ______________________________________                                        1    None.sup.a     --       13   14   21   23                                2    1,6-hexanediol 0.90     17   17   21   23                                3    1,10-decanediol.sup.b                                                                        1.28     18   21   27   29                                4    triethanol amine                                                                             0.75     20   21   25   25                                5    diethanol methylamine                                                                        0.90     21   23   25   27                                6    dethanol ethylamine                                                                          0.98     22   22   25   27                                7    1,12-dodecanediamine.sup.b                                                                   1.50     --   17   18   20                                ______________________________________                                         .sup.a Residual water acts as a crosslinker.                                  .sup.b Dissolved in chloroform and coated on wet tensile sample strip and     dried.                                                                        .sup.c Parts by weight per 100 parts by weight of polymer in the latex.  

EXAMPLE VI

The polymers of the present invention present a unique balance betweenrapid cure at low temperatures (evidencing quick, efficient release ofthe blocking agent) and stability, especially to hydrolysis in thepresence of water. This unique balance is struck by the use of both thearomatic diisocyanate and the specified blocking agents in thepreparation of the novel ethylenically unsaturated blocked aromaticisocyanates. The following data shows that the polymers of the inventionhave good stability to hydrolysis. Polymer latex sample B prepared inExample III is employed. Testing consisted of wet tensile strengthbefore and after aging at room temperature.

    ______________________________________                                                    Wet Tensile                                                       Sample B    Strength, psi     Time Aged                                       Test Strip  Original   Aged      (days)                                       ______________________________________                                        Cured                                                                         3' at 100° C.                                                                      20         14         50                                                                 12         100                                         3' at 125° C.                                                                      22         19         50                                                                 17         100                                         3' at 150° C.                                                                      23         19         50                                                                 18         100                                         Aged in presence                                                              of 0.75 parts by                                                              wt. of triethanol                                                             amine                                                                         Cured 3' at 22         19         50                                          100° C.                                                                            22         17         100                                         ______________________________________                                    

EXAMPLE VII

Expanding on Example VI, other polymers of this invention were preparedfollowing the procedures given in Examples I and II, and evaluated as totheir stability to hydrolysis and their ability to impart wet tensilestrength to non-woven fibers. Original and aged wet tensile strength ofimpregnated non-woven paper was determined following the procedure inExample III. Results are reported in the following tables.

    __________________________________________________________________________         Wt. Percent                                                              Polymer                                                                            Vinylidene                                                               Sample                                                                             Monomer                                                                              Diisocyanate.sup.a                                                __________________________________________________________________________    H    94 EA.sup.b                                                                           ##STR24##                                                        I    96 EA.sup.b                                                                           ##STR25##                                                        J    87 EA.sup.b 10 VCN.sup.c                                                              ##STR26##                                                        K    94 EA.sup.b 2 AA.sup.d                                                                ##STR27##                                                        L    76 EA.sup.b 20 Sty.sup.e                                                              ##STR28##                                                        M    70 BD.sup.f 20 Sty.sup.e                                                              ##STR29##                                                        __________________________________________________________________________     .sup.a Weight percent diisocyanate = 100%  weight percent of vinylidene       monomer(s)                                                                    .sup.b Ethyl acrylate                                                         .sup.c Acrylonitrile-                                                         .sup.d Acrylic acid                                                           .sup.e Styrene-                                                               .sup.f Butadiene-                                                        

The polymers above, in latex form, were used to impregnate saturationgrade, bleached Kraft paper (11 mils thick) following the procedure inExample III. The test sample strips were then evaluated for theiroriginal wet tensile strength. Following Example VI, after allowing thepolymer latex samples to age, test sample strips were again prepared andthe wet tensile strength measured. Results are reported below.

    ______________________________________                                                Wet Tensile          Average                                          Latex   Strength.sup.1, psi  % Decrease                                       Sample  Original  Aged      Days   Per Day                                    ______________________________________                                        B       20        12        100    0.40                                       H       20        17        45     0.33                                                         14        100    0.30                                       I       15         8        47     0.99                                       J       20        17        30     0.50                                                         15        60     0.42                                       K        16.sup.2 11        34     0.92                                       L       21        19        29     0.33                                                         15        64     0.45                                       M        22.sup.3 15        50     0.64                                       ______________________________________                                         .sup.1 Cured 3 minutes at 100° C., no crosslinker added                .sup.2 At 15th day                                                            .sup.3 At 70th day                                                       

The data shows that the polymers of the present invention, samples B andH to M, prepared using the novel ethylenically unsaturated blockedaromatic diisocyanates, impart good wet tensile strength to non-wovenfibers, and have unexpectedly good stability to hydrolysis when storedas a latex. If a crosslinker and/or higher cure temperatures areemployed with the novel polymers, higher original and aged wet tensilestrengths are obtained. For example, sample I, which showed the leaststability, can be cured at 150° C. using 0.75 parts of triethanolamine(after 47 days of aging) to yield a wet tensile strength of 19 psi.

EXAMPLE VIII

If, instead of reacting the hydroxyl-containing monomer with thearomatic diisocyanate, the blocking agent is first reacted with thearomatic diisocyanate, different variations in the structure of theethylenically unsaturated blocked aromatic diisocyanate can be prepared.For example, in Example I, procedure A, the following diisocyanate wasprepared: ##STR30## When the methylbenzotriazole was first reacted withthe 2,4-toluene diisocyanate, followed by reaction with theβ-hydroxyethyl acrylate, the structure is: ##STR31##

The diisocyanate prepared by the reverse addition of materials can beeasily polymerized with vinylidene-terminated monomers via emulsiontechniques, and is useful in latex form as a binder for non-wovenfibers. The following data shows this fact.

    ______________________________________                                        Latex   Wet Tensile Strength, psi.sup.b                                       Sample  80° C.                                                                           100° C.                                                                          125° C.                                                                        150° C.                            ______________________________________                                        p.sup.a 15        16        19      22                                        ______________________________________                                         .sup.a 96% by weight ethyl acrylate, 4% by weight diisocyanate                .sup.b 3 minute cure                                                     

The polymer was prepared following the procedure in Example II. Testingfollowed the procedure in Example III. Use of an added crosslinkerraises the value of the wet tensile strength.

EXAMPLE IX

Following procedures in previous Examples, the diisocyanates made inExample I as C and E were interpolymerized with ethyl acrylate andβ-hydroxyethyl methacrylate. The polymers were evaluated in latex formas binders for non-woven paper. Data is as follows:

    ______________________________________                                        Latex     Wet Tensile Strength, psi                                           Sample    100° C.                                                                           125° C.                                                                            150° C.                               ______________________________________                                        Q.sup.a   17         18          18                                           R.sup.b   15         21          24                                           ______________________________________                                         .sup.a 93.8% ethyl acrylate, 1.5% hydroxyethyl methacrylate, 4.7%             diisocyanate E                                                                .sup.b 95.6% ethyl acrylate, 1.3% hydroxyethyl methacrylate, 3.1%             diisocyanate C                                                           

EXAMPLE X

Diisocyanate sample B from Example I was interpolymerized with ethylacrylate via an emulsion polymerization process. The recipe was:

    ______________________________________                                        Ethyl acrylate, grams                                                                              20.4                                                     Diisocyanate B.sup.a, grams                                                                        12.9                                                     Water, milliliters   68                                                       Sodium lauryl sulfonate,                                                                           10                                                       milliliters.sup.b                                                             Ammonium persulfate, grams                                                                         6.5                                                      ______________________________________                                         ##STR32##                                                                     .sup.b 10% by weight in water                                            

The ethyl acrylate, diisocyanate B, sodium lauryl sulfate solution, and4 milliliters of water were mixed together in a stirred dropping funnel.2 milliliters of the mixture was then placed into the reactor vesselwith 62 milliliters of water and the ammonium persulfate (dissolved in 2milliliters of water). The temperature was raised to 50° C. and held at55°±2° C. throughout the run. The remaining monomer mixture was addedover a 20 minute period. Total reaction time was 1.5 hours. Percentconversion of monomers to polymer was 96% based on total solids. Theexample demonstrates that interpolymers containing high weight percentsof the ethylenically unsaturated blocked aromatic diisocyanates of thisinvention can be readily prepared. In this example, the interpolymercomposition was about 61% by weight ethyl acrylate and about 39% byweight of the specific diisocyanate.

I claim:
 1. An article comprising (1) a nonwoven fiber coated orimpregnated with (2) a polymer comprising from about 0.1 percent to 100percent by weight of polymerized units of an ethylenically unsaturatedblocked aromatic diisocyanate of the formula ##STR33## wherein R ishydrogen or a methyl or ethyl radical; A is a carbonyloxyalkyleneradical containing 2 to about 8 carbon atoms or an aralkylene radicalcontaining 7 to about 12 carbon atoms; B is a bivalent aromatic radicalselected from the group consisting of arylene, naphthalene, and thestructure ##STR34## where R is defined as above; Y is O, S, or--CH₂)_(n) ; n=0 to 3; and X is the radical fragment remaining after ahydrogen atom is removed from the nitrogen atom of an oxime,benzimidazole, pyrazole, benzotriazole, caprolactam, thiocaprolactam, orp-nitroaniline, and up to 99.9 percent by weight of polymerized units ofa copolymerizable vinylidene monomer.